An object of the present invention is to provide a copolymer polyamide which has excellent strength, high-temperature strength, low water absorbance, low blocking properties, releasability and plasticizing time stability, and a copolymer polyamide composition which has excellent vibration fatigue characteristics, surface appearance and continuous productivity. A copolymer polyamide of the present invention is obtained by polymerizing (a) at least one alicyclic dicarboxylic acid, (b) one diamine having 8 or more carbon atoms, and (c) at least one copolymer component selected from the group consisting of the following (c-1) to (c-3): a (c-1) dicarboxylic acid other than the alicyclic dicarboxylic acid; a (c-2) diamine having fewer carbon atoms than the (b) diamine; and a (c-3) lactam and/or aminocarboxylic acid, and the copolymer polyamide satisfies specific conditions.